How to add all variables its second degree in lm()? [duplicate]

Question

This question already has an answer here:

• R:fit dynamic number of explanatory variable into polynomial regression 1 answer

I have a dataframe with 16 variables. When I do multiple linear regression I do the following:

fit <- lm(y ~ .,data=data)

Now, I know how to add a second degree term of one of the variables:

fit2 <- lm(y ~ poly(x1,2) + .,data=data)

But now I don't want to write this out for all of my 16 variables. How can I do this in an easy way for all my variables?

Answer 1

When assuming the first variable in data is our 'y', we get this:

as.formula(
    paste('y ~',paste('poly(',colnames(data[-1]),',2)',collapse = ' + ')
)